How do electric trains switch voltage / power systems?

[norbitonflyer]

How do electric trains in foreign parts, capable of working on both AC and DC - or on different voltages - from the overhead, switch over?

Are there clever circuits which detect what is coming through the pantographs and switch to the appropriate circuitry in the loco? Does the OHLE at the changeover point switch between the two systems once the appropriate switches have been thrown, and/or pantographs lowered and raised, in the loco?

 

[Bald Rick]

Are there clever circuits which detect what is coming through the pantographs and switch to the appropriate circuitry in the loco? Does the OHLE at the changeover point switch between the two systems once the appropriate switches have been thrown, and/or pantographs lowered and raised, in the loco?

All of those things can happen, yes!

 

[Spartacus]

How do electric trains in foreign parts, capable of working on both AC and DC - or on different voltages - from the overhead, switch over?

Are there clever circuits which detect what is coming through the pantographs and switch to the appropriate circuitry in the loco? Does the OHLE at the changeover point switch between the two systems once the appropriate switches have been thrown, and/or pantographs lowered and raised, in the loco?

On this particular one I gathered from the staff comments that they'd decided to omit the clever circuitry on cost ground and instead used two pantographs on different circuits which were operated manually. This apparently wasn't the first time it had gone wrong, but was either the most serious or most public.

 

[Minerva05]

How do electric trains in foreign parts, capable of working on both AC and DC - or on different voltages - from the overhead, switch over?

Are there clever circuits which detect what is coming through the pantographs and switch to the appropriate circuitry in the loco? Does the OHLE at the changeover point switch between the two systems once the appropriate switches have been thrown, and/or pantographs lowered and raised, in the loco?

I seem to recall on the Eurostar 373s, when coming onto a changeover point, the driver drops the pantograph(s), selects the appropriate system using a rotary switch and then, having passed the correct line side sign stating the train is fully on the ‘new’ system raises the pan(s) again. This was observed from ‘drivers eye view’ video and a book called ‘Eurostar from the footplate’ I think the TGVs might be similar?

What would happen if the switch was accidentally put on the wrong voltage, I don't know…

 

[norbitonflyer]

I seem to recall on the Eurostar 373s when coming onto a changeover point, the driver drops the pantograph(s), selects the appropriate system using a rotary switch and then, having passed the correct line side sign stating the train is fully on the ‘new’ system raises the pan(s) again. This observed from ‘drivers eye view’ video and a book called ‘Eurostar from the footplate’ I think the TGVs might be similar? What would happen if the switch was accidentally put on the wrong voltage, I dont know…

Or indeed not moved in time. Those videos seem to show an awful lot of work to be done by the driver whilst the train is in motion, which must be a distraction.

Can't balises be used to cause the changeover process (drop, change circuits, raise) to be made automatically?

 

[The exile]

Which riases the question as to how electric trains in foreign parts capable of working on both AC and DC - or on different voltages - from the overhead, switch over. Are there clever circuits which detect what is coming through the pantographs and switch to the appropriate circuitry in the loco? Does the OHLE at the changeover point switch between the two systems once the appropraite switches have been thrown, and/or pantographs lowered and raised, in the loco?

Usually separate pantographs and a neutral section if the changeover is between stations. System change in stations (Aachen or Venlo for example) where there was also loco change usually required expensive switching gear for the OHLE itself - which was ditched at the earliest opportunity!

 

[martin2345uk]

I seem to recall on the Eurostar 373s when coming onto a changeover point, the driver drops the pantograph(s), selects the appropriate system using a rotary switch and then, having passed the correct line side sign stating the train is fully on the ‘new’ system raises the pan(s) again. This observed from ‘drivers eye view’ video and a book called ‘Eurostar from the footplate’ I think the TGVs might be similar? What would happen if the switch was accidentally put on the wrong voltage, I dont know…

373s and 374s "know" what voltage setting they are expecting at the changeovers and won't let you raise the wrong pan (or the right pan with the wrong network settings)(374s give you an error message if you try).

There are balises that will automatically drop the pans if you get too close to the changeover point without lowering them manually.

 

[MarcVD]

Recent signalling systems allow to make that fully automatic.

With older hardware, the switch is always under the control of the driver.
He will first encounter a panel that tells him to drop the pantograph. If he doesn't, his pantograph will short the active catenary to the neutral section that separate both voltages, and cause the substation to fail.
Then, with all pantographs down, he will have to select a new position on his "administration" rotary switch. This selects the network (like SNCF) and the voltage (like 25 kV 50 Hz). A panel on the ground is usually placed to indicate where this action must take place. This action will select which pantograph to use and configure the loco internal circuitry for the correct voltage. It does not select which security system to use, however, because the electric and signalling transitions are not necessarily located at the same place.
And finally he will encounter yet another board that will instruct him to raise the pantograph. A detection device will check that the voltage present matches his selection and completely switch off the loco if not.
All pantographs are usually connected together, so that in case one fails, another one can be used, usually with severe restrictions, and provided of course that it is geometrically compatible with the catenary. The choice of equipment to be used inside the loco is done by its internal circuitry, I.e. big relays and switches.
Here is an example of a voltage change zone, between belgian 3 kV DC and French 25 kV AC. We are in Quevy, right under the neutral zone, looking towards France. Trains reaching that point already have their DC panto down, must now select "SNCF 25 kV", and wait for the "panto up" sign to appear before restoring power.

Picture from https://www.foudurail.org/belge/quevy.html

And here is a picture of the driving post f a belgian HLE 16 quadri-voltage loco, with, at the right of the rheostat controls, the administration rotary switch.

 

[Gordon]

Geneve Cornavin used to have a platform with overhead wires switchable between SNCF's 1500v DC and Swiss 16kV ac. A combination of switchable gear and driver knowledge of where to raise and lower pantographs, coast in with pan down etc overcame any problems.

At Domodossola - Swiss 16kV as far as the north (Simplon) end of the station throat and Italian 3000v DC in the station was overcome by pan down coasting and shunting by the loco from the 'other' side.

For example an SBB Re4/4 would come through from Brig, coast pan down into Domo station, uncouple and be shunted back as fa as the 'sweet spot' at the 'Swiss' end of the station by an FS electric.

In France there are a number of places where 1500v DC meets 25kV AC, and SNCF developed numerous bi-current loco types to overcome this; but there are also places where 'modern day' extension of electrification on 1500v DC routes electrified in the 1930s-50s has been at 1500v DC for practical reasons.

 

[MarcVD]

Stations with switchable tracks are not very numerous and now tend to disappear. Geneva is gone, Quevy (Belgian-French border on Paris to Brussels) is gone too, Luxembourg also, Aachen will go in the next few years. Remains Jeumont (French-Belgian border on Paris-Liege) but I'm not sure it's still operational, Basel, and I don't know where (Venlo?) between Germany and the Netherlands. May be a few other examples, notably in eastern Europe, that I don't know about.

Many stations are just divided in two sectors, and locos enter the "wrong sector" coasting with their panto down, and have to be pushed back. Domodossola, Chiasso, Brennero, Spielfeld-Strass, Dobova are of this type.

A special case is Vintimiglia, at the French-Italian border. Normally in 3 kV DC territory but voltage there is only 1,5 kV so that bivoltage French locos can enter.

Anyone knows how Modane works today ? The French line to there used to be 3rd rail powered, so French locos entered there on 1500V 3rd rail and Italian ones on 3 kV catenary. How does it work now that the 3rd rail has been replaced by catenary ? Is it like Ventimiglia?

 

[AdamWW]

Stations with switchable tracks are not very numerous and now tend to disappear. Geneva is gone, Quevy (Belgian-French border on Paris to Brussels) is gone too, Luxembourg also, Aachen will go in the next few years. Remains Jeumont (French-Belgian border on Paris-Liege) but I'm not sure it's still operational, Basel, and I don't know where (Venlo?) between Germany and the Netherlands. May be a few other examples, notably in eastern Europe, that I don't know about.

Bad Bentheim (Netherlands/Germany) was certainly voltage switchable at least until quite recently - the Amsterdam-Berlin trains changed locomotives there.

 

[rvdborgt]

Bad Bentheim (Netherlands/Germany) was certainly voltage switchable at least until quite recently - the Amsterdam-Berlin trains changed locomotives there.

You don't necessarily need switchable tracks to change locomotives, but it does make it easier. Bad Bentheim still has switchable tracks.

 

[Amalie]

Anyone knows how Modane works today ? The French line to there used to be 3rd rail powered, so French locos entered there on 1500V 3rd rail and Italian ones on 3 kV catenary. How does it work now that the 3rd rail has been replaced by catenary ? Is it like Ventimiglia?

According to Openrailwaymap the station itself is 1.5Kv, but I’m not sure how accurate that is.

I do wonder what the furthest East 1,5Kv DC trains can go to on their own power. Is it Bad Bentheim or Modane?

Stations with switchable tracks are not very numerous and now tend to disappear. Geneva is gone, Quevy (Belgian-French border on Paris to Brussels) is gone too, Luxembourg also, Aachen will go in the next few years. Remains Jeumont (French-Belgian border on Paris-Liege) but I'm not sure it's still operational, Basel, and I don't know where (Venlo?) between Germany and the Netherlands. May be a few other examples, notably in eastern Europe, that I don't know about

Venlo is indeed the only Dutch station with switchable catenary, but they also would like to remove it.

 

[LNW-GW Joint]

373s and 374s "know" what voltage setting they are expecting at the changeovers and won't let you raise the wrong pan (or the right pan with the wrong network settings)(374s give you an error message if you try).
here are balises that will automatically drop the pans if you get too close to the changeover point without lowering them manually.

Added to which is that Eurotunnel has a high catenary for the outsize shuttle trains, so 373/374s need extra long pantographs for the tunnel section.

 

[Beebman]

Anyone knows how Modane works today ? The French line to there used to be 3rd rail powered, so French locos entered there on 1500V 3rd rail and Italian ones on 3 kV catenary. How does it work now that the 3rd rail has been replaced by catenary ? Is it like Ventimiglia?

After the replacement of the 3rd rail it worked like Ventimiglia with Italian locos changing between 3000V and 1500V just to the east of the station. Here's a photo of the start of the 3000V from Wikimedia Commons taken in 2013:



I'm unable to find any more recent references to the situation at Modane but I assume it's still the same today.

 

[AdamWW]

You don't necessarily need switchable tracks to change locomotives, but it does make it easier. Bad Bentheim still has switchable tracks.

Indeed not - and the engine changes would have been much more interesting if they didn't.

Stations with switchable tracks are not very numerous and now tend to disappear. Geneva is gone, Quevy (Belgian-French border on Paris to Brussels) is gone too, Luxembourg also, Aachen will go in the next few years. Remains Jeumont (French-Belgian border on Paris-Liege) but I'm not sure it's still operational, Basel, and I don't know where (Venlo?) between Germany and the Netherlands. May be a few other examples, notably in eastern Europe, that I don't know about.

Ah also there must be switchable tracks at Zweisimmen for the gauge changing trains.

Given they are push pull trains which change from pull to push at the gauge change, the obvious way to me would be to have the voltage change part way down the platform and keep each engine on its own voltage (and gauge). But - no doubt for excellent reasons - it works the other way round.